Yeah, unfortunately, it wasn't me that was firing the pistol. The shot before the kaboom was obviously the squib, but when he turned to me and said "What's wrong, it won't shoot", I thought that the casing just didn't eject, and told him to tap rack and go. He did, and then the kaboom.
Nothing sounded out of the ordinary, and because this was his first time shooting a pistol, he couldn't know anything was wrong either, on the squib round.
No one was hurt, all I need is a replacement barrel, and we're good to go. I already have a big pile of new parts that're going to go on the pistol, including a new guide rod and plug, new slide stop, and new recoil spring, so the only thing that needs replacing is a bushing and a barrel.
The maker of the reloads has been in contact with me, and, as any reloader knows, this was simply a matter of odds. When you reload 50,000 rounds of .45, you'll eventually run into one that doesn't quite go right, and it just so happened to be the fifteenth round out of my pistol.
#### happens, and then you die. It's all getting worked out.
Oh, and here's some new photos: